var a='aa';
dynamic c='34';
Object d='www';

const b=23;
final aa=23;
late int bb=45;


//? 空安全
int? pp=90;


bool isNodel(int act){
  return  act ==0;
}



void main(){
  String a='hello world';
  a='23';
  print(a);
  var  b='dart';
  print(a);
  print(b);
  Object c='opp';
  c=34;
  print(c);
  dynamic name ='libai';
  print(name);
  const pp='op';
  final opp='opp';
  print(pp);
  print(opp);
}

/**
 * 1.区分Object 和类型如String 定义变量的区别
 *
 * 2.区分const,static,dynamic ,final 的区别
 *  可见文章 https://juejin.cn/post/6844903897123799054#heading-5
 *
 */